Heretofore, a tire pressure measuring apparatus provided in a vehicle for measuring tire pressure has been known (for example, Patent Document 1). A conventional tire air pressure measuring apparatus includes air pressure sensor modules, a receiver, an ECU and a display unit.
Each of the air pressure sensor modules is provided with a tire and measures a tire air pressure to generate an air pressure data signal of the measured air pressure. Each of the air pressure sensor modules generates an identification data signal for identifying itself among the air pressure sensor modules. Each of the air pressure sensor modules transmits the air pressure data signal and the identification data signal to the receiver at predetermined transmitting intervals (for example, 1 (min.)) by wireless communicating with the receiver at the predetermined transmitting intervals. Each of the air pressure sensor modules rotates together with the tire.
The receiver communicates wirelessly with the air pressure sensor modules. The receiver receives the air pressure data signals and the identification data signals, and outputs them to the ECU. The ECU classifies each of the air pressure data signals into each of segments provided for the tires based on the signals transmitted from the receiver and identifies the air pressure of each of the tires based on the air pressure data signal in each of the segments to display it on the display unit. In case where the receiver has not received the air pressure data signal of any one of the segments for an error determining duration, the ECU determines that an error has occurred in the air pressure sensor module of the one of the segments and displays the determination on the display unit. Here, the error determining duration is equal to or longer than the predetermined transmitting interval and may be 60 (min.) for example.
Patent Document 1: Japanese Patent Application Laid-Open NO. 2003-237327